JPH03241688A - Induction heating roll device - Google Patents

Abstract

PURPOSE:To improve the uniform heating property and power factor by connecting the U-V phase of a three-phase AC power source to two serial electromagnetic coils in one closed magnetic path, connecting one end of one electromagnetic coil in the other closed magnetic path to the middle connection section of two serial electromagnetic coils, and connecting the other end to the W phase. CONSTITUTION:Two independent closed magnetic paths are provided along the axial direction of a rotating roll, and the closed magnetic paths can be formed by installing three or less iron cores 4. Leg iron cores on both ends can be omitted, because magnetic flux paths are formed by flanges 2 on both ends. The leg iron core 4 at the center section may be just one, or two leg iron cores 4 may be. provided, and a magnetic flux bad conductor such as stainless steel is provided between them, or an air gap may be provided. An iron core 5 and electromagnetic coils 6-8 are provided in each closed magnetic path. A three-phase AC power source is fed to the coils 6-8, the U-V phase is connected to two serial magnetic coils 6, 7 in one of the independent closed magnetic paths, one end of the electromagnetic coil 8 in the other closed magnetic path is connected to the middle connection section of two electromagnetic coils, and the other end is connected to the W phase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a metal induction heating roll using a three-phase AC power source with a commercial frequency.

[Prior Art] In recent years, an induction heating method has generally been used as a heating means for metal heating rolls. The reason for this is that electricity is a clean means of heating, and induction heating can efficiently convert electricity into heat, and is easy to maintain and manage.
This is because the device can be made durable.

Conventional induction heating rolls use single-phase AC power;
Alternatively, a method using a three-phase AC power source is known. For example, as an example of a method using a three-phase AC power supply, as proposed in Japanese Patent Publication No. 59-3034, three independent closed magnetic paths are provided inside the roll, and the internal closed magnetic paths are It houses an induction coil and performs induction heating using a star or delta connection using a three-phase AC power supply.

[Problems to be solved by the invention] However, in the above-mentioned conventional technology, there is a problem that the heat conversion efficiency (power factor) of electric power is low and electric power is wasted, and it is necessary to provide three closed magnetic circuits. Due to this, there was an important problem that heat was not generated in two parts of the roll directly above the closed magnetic circuit (yoke core), and the heat uniformity was not very good.

In order to improve the problems of the prior art, the present invention uses a three-phase power source as a power source, has two closed magnetic circuits, and uses a specific wiring system to improve uniform heating and increase the power output. The purpose of this invention is to provide an induction heating roll with a high heating rate.

[Means to solve the problem] In order to achieve the above object, the present invention has the following configuration.

That is, the induction heating roll device of the present invention provides two mutually independent closed magnetic paths along the axial direction of the roll inside a rotating metal roll, and provides an iron core and an electromagnetic coil inside each of the closed magnetic paths. The electromagnetic coil is powered by an alternating current three-phase power supply having a commercial wave number, and has two coils in which the UV phase of the three-phase alternating current power supply is housed in one of the independent closed magnetic circuits. Connecting one of the electromagnetic coils connected to the series power supply coil and housed in the other of the independent closed magnetic circuits to the intermediate connection part of the two electromagnetic coils in series, The other one is connected to the W phase of the three-phase AC power supply.

In the above configuration, it is preferable that a heat pipe is inserted along the axial direction of the metal roll.

[Function] According to the configuration of the present invention, the U- of the three-phase AC power supply
The V phase is connected to two series power supply coils housed in one of the independent closed magnetic circuits, and one power supply coil housed in the other of the independent closed magnetic circuits. One of the electromagnetic coils is connected to the intermediate connection between the two electromagnetic coils in series, and the other is connected to W of the three-phase AC power source.
Since it is connected to the phase, uniform heat generation and performance can be improved, and the power factor can be significantly improved, allowing for effective use of electric power. In addition, the number of closed magnetic circuits has been reduced from three to two, so the non-heat generating part (the boundary between the closed magnetic circuits)
is reduced from two to one, and uniform heating is therefore possible. Furthermore, since a three-phase AC power source with a commercial wave number can be effectively used, there is a great advantage in terms of cost.

Further, according to a preferred embodiment of the present invention, the heat pipe is inserted along the axial direction of the metal roll, so that the metal roll can have excellent heat uniformity in the axial direction.

[Example 1] Hereinafter, an example of the present invention will be described in more detail with reference to the drawings. Note that the present invention is not limited to the following examples.

FIG. 1 is a cross-sectional view of a roll according to one embodiment of the present invention, viewed from the side. In Fig. 1, 1 is a metal roll, 2 is a flange, 3 is a central shaft, 4 is a leg core, 5 is a yoke core, 6 to 8
1 is an electromagnetic coil, 9 is a lead wire, 10 is a heat pipe insertion port, 11 is a heat pipe, 12 is a machine base, 13 is a rotation stopper, 14 is a bearing between the flange 2 and the machine base 12, 1
5 is a bearing between the central shaft 3 and the flange 2.

Further, FIG. 2 shows a schematic diagram of the wiring system of the present invention.

The operation of an embodiment of the present invention configured as described above will be described below.

Inside a rotating roll 1 made of carbon steel material, two mutually independent closed magnetic paths are provided along the axial direction of the roll.

Such a closed magnetic path can be constructed by installing three or less leg cores 4. The leg cores at both ends can also be omitted. In this case, one piece is sufficient. This is because the flanges 2 form magnetic flux paths at both ends. The leg core 4 can be made by laminating silicon steel plates or amorphous alloy thin films, for example, in the shape of a disk (by drilling or providing slits).Another example of the leg core 4 is a carbon steel plate. It can also be made into a disk shape with slits.

Furthermore, in the closed magnetic path, the leg iron core 4 in the center may be one piece (or one piece), but two pieces (or two pieces) may be provided, and a magnetic flux poor conductor such as stainless steel is provided between them, or an air gap is provided between them. It's okay.

A yoke core 5 and an electromagnetic coil 6.7.8 are provided inside each of the closed magnetic circuits. Preferably, the coils 6.7 are wound in the same direction. On the other hand, the winding direction of the coil 8 is
It may be in the same direction as the coil 6.7 or in the opposite direction.

The electromagnetic coils 6, 7. 8 supplies an AC three-phase power source consisting of a commercial frequency (for example, 50 Hz or 60 Hz in Japan) as a power source. The wiring system consists of two series electromagnetic coils (6,
7), and one of the electromagnetic coils (8) housed in the other of the independent closed magnetic circuits is connected to the intermediate connection part of the two electromagnetic coils in series. , the other is connected to the W phase of the three-phase AC power supply.

In the embodiment of the present invention, it is not necessary to use a heat pipe, but as a preferable example, the heat pipe 11 is inserted along the axial direction of the metal roll 1. This is to further improve uniform heating of the roll by utilizing evaporation and condensation of the working fluid (for example, pure water) in the heat pipe.

Heat pipe installation means include, for example, the technique of expanding a heat pipe (Japanese Patent Application Laid-Open No. 63-91991) and the technique of filling the gap with molten metal (Japanese Patent Application No. 1-137673).
, and others such as Japanese Unexamined Patent Publication No. 55-122037 can be used.

Example 1 The device shown in Figures 1 and 2 (roll length 250 mm, 10 mm, roll thickness 400 mm) was used except that no heat pipe was used, and the standard winding ratio of 6° 7.8 was used. , winding 6: winding 7: winding 8100T: 100T: 17
3T, and when connected to a 60 Hz, 220 volt three-phase AC power supply, the U and VXW (7) current values were 3 each.
3.5A.

34, OA, 35. Became OA. Further, the voltage between UV and V was 208V.The voltage between XV and W was 2o3v1W-U was 208V. Furthermore, when we calculated the power factor,
We were able to obtain a high value of 83%.

In addition, when the temperature of the roll surface was measured, it was 148°C at the center of the roll and 146°C at both ends of the roll, and there was no particular temperature drop on the roll surface corresponding to leg core 4, so it was heated uniformly. I was able to do that.

Example 2 Using the apparatus shown in FIGS. 1 and 2, a heat pipe 1
In No. 1, 18 pieces of working liquid pure water each having a diameter of 13 mm were arranged circumferentially inside the roll by the tube expansion method. Other conditions were the same as in Example 1.

As a result, a high power factor of 83% could be obtained.

Further, when the temperature of the surface of the roll was measured, it was 148°C at the center of the roll, 148°C at both ends of the roll, and the temperature was within 148±1°C over the entire surface of the roll. Of course, there was no particular temperature drop on the roll surface corresponding to the leg core 4, and uniform heating was possible.

Comparative Example Among the devices shown in FIG. 1, the independent closed magnetic circuit portions were changed to create three equal closed magnetic paths. Using the wiring system shown in Fig. 4, its effectiveness was verified through experiments.

Table 1 shows the results of Example 1 as well as the wiring system and results of Comparative Example.

Table 1 As shown in Table 1, the heating method shown in Example 1 has a stable current value and the highest power factor;
In the comparative examples shown in FIG. 3-e and FIGS. 4a-c (of which the connection shown in FIG. 3 is the connection shown in Japanese Patent Publication No. 3034/1983), the current value was not stable and the power factor was low.

[Effects of the Invention] According to the present invention described above, the U of the three-phase AC power supply
- Connect the V phase to two series power supply coils housed in one of the independent closed magnetic circuits, and one coil housed in the other of the independent closed magnetic circuits. One of the electromagnetic coils is connected to the intermediate connection part of the two electromagnetic coils in series, and the other is connected to the W phase of the three-phase AC power supply, so it is possible to improve uniform heating properties and , the power factor can be significantly improved, and electric power can be used effectively. In addition, the number of closed magnetic circuits has been reduced from three to two, so
The number of non-heat generating parts is reduced from two to one, thus enabling uniform heating. Furthermore, since a three-phase AC power source with a commercial wave number can be effectively used, there is a great advantage in terms of cost.

Further, according to a preferred embodiment of the present invention, since the heat pipe is inserted along the axial direction of the metal roll, the heat uniformity of the metal roll in the axial direction can be further improved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an induction heating roll device showing an embodiment of the present invention, Fig. 2 is a Scott connection diagram used in the embodiment,
3 and 4 are circuit diagrams using a three-phase power source as a comparative example. 1... Metal roll, 2... Flange, 3... Center shaft, 4... Leg core, 5... Yoke core, 6.7.8
...Electromagnetic coil, 9...Lead wire, 10...Heat pipe insertion port, 11...Heat pipe, 12...
Machine base, 13... Detent fitting, 14... Flange 2
and the machine stand 12, 15... a bearing between the center shaft 3 and the flange 2. 1 2 Figure 3 U ■ Figure 4

Claims (2)

[Claims] (1) Inside a rotating metal roll, two mutually independent closed magnetic paths are provided along the axial direction of the roll, and an iron core and an electromagnetic coil are provided inside each of the closed magnetic paths, and the electromagnetic coil has a commercial wave frequency. The U-V phase of the three-phase AC power source is connected to two series power coils housed in one of the independent closed magnetic circuits. At the same time, one of the electromagnetic coils housed in the other of the independent closed magnetic circuits is connected to the intermediate connection part of the two electromagnetic coils in series, and the other is connected to the three-phase AC power supply. An induction heating roll device characterized in that it is connected to the W phase of the W phase. (2) The induction heating roll device according to claim 1, wherein a heat pipe is inserted along the axial direction of the metal roll.